Diode and Zener I-V Curve: Circuit, Measurements and Online Simulator

To build this Diode and Zener I-V Curve circuit you need an I-V curve tracer and a 5.1 V Zener diode. An I-V curve tracer sweeps −10…+10 V across a 5.1 V Zener: a diode knee at about 0.65 V forward, and a sharp breakdown at −5.1 V in reverse. Make the 2 connections in the wiring table, press Run, and and read Vf and breakdown off the panel. Change the Zener to 9.1 V, or put a 1 kΩ resistor in its place and see a straight line: Ohm's law.

Open this circuit in the free Electronics bench simulator

Parts list

Qty	Part	What it does
1	I-V Curve Tracer	Plots current against voltage for the part between A and K — a diode's knee, an LED's forward voltage, a Zener's breakdown, a resistor's straight line. It sweeps −V…+V through 100 Ω and reads Vf at +1 mA and breakdown at −1 mA. Wire A to the anode side, K to the cathode side.
1	5.1 V Zener diode	Conducts forward like a diode; reversed, it holds its Zener voltage — a simple regulator with a series resistor. The stripe is K.

Wiring

#	From	To
1	I-V Curve Tracer A	5.1 V Zener diode A
2	5.1 V Zener diode K	I-V Curve Tracer K

Step by step

Open the electronics bench. Open the BitForBytes Embedded Lab in your browser. A circuit with no microcontroller runs on the analog bench: no install or account is needed.
Add the parts. Add an I-V curve tracer and a 5.1 V Zener diode from the parts palette (Instruments, Power, Passive and Semiconductors).
Wire 1. Connect I-V Curve Tracer A to 5.1 V Zener diode A.
Wire 2. Connect 5.1 V Zener diode K to I-V Curve Tracer K.
Run and measure. Press Run and read Vf and breakdown off the panel. Change the Zener to 9.1 V, or put a 1 kΩ resistor in its place and see a straight line: Ohm's law.

Lab sheet

// Electronics bench: the I-V curve of a Zener diode
//
// A curve tracer drives a voltage across the part and measures the current.
// Forward, a silicon junction conducts past ~0.6 V: the current rises
// exponentially (Shockley: I = Is·(e^(V/nVt) − 1)).
// Reversed, almost no current flows until the Zener voltage, where it breaks
// down and holds the voltage nearly constant: that is how it regulates.
//
// The tracer runs a DC sweep, the way SPICE's .DC analysis does.

What to try

Press Run and read Vf and breakdown off the panel. Change the Zener to 9.1 V, or put a 1 kΩ resistor in its place and see a straight line: Ohm's law.

Frequently asked questions

How do I wire the Diode and Zener I-V Curve circuit?

Make 2 connections: I-V Curve Tracer A to 5.1 V Zener diode A; 5.1 V Zener diode K to I-V Curve Tracer K.

What parts do I need for the Diode and Zener I-V Curve?

An I-V curve tracer and a 5.1 V Zener diode.

Can I simulate the Diode and Zener I-V Curve online for free?

Yes. The BitForBytes Embedded Lab solves the circuit in time, the way SPICE does (nodal analysis with real diode, transistor and capacitor models), and gives you a bench power supply, function generator, oscilloscope and multimeter to measure it — free, in the browser.

What does this circuit show?

An I-V curve tracer sweeps −10…+10 V across a 5.1 V Zener: a diode knee at about 0.65 V forward, and a sharp breakdown at −5.1 V in reverse.